本发明涉及一种电渣重熔含B型9Cr耐热钢用渣系，包含：按质量百分比计的CaF₂：50‑60％，Al₂O₃：15％‑25％，CaO：15％‑25％，MgO：3％‑8％，B₂O₃：0.5％‑3％,余量为杂质，杂质含量≤1％，前述各项之和为100％；所述杂质中包含不稳定氧化物SiO₂，不稳定氧化物SiO₂占渣系≤0.8％。所述渣系可用于电渣重熔生产含B型9Cr耐热钢，如COST‑FB2钢或CB2钢等，该渣系的使用能减少B元素的烧损，使B含量沿铸锭高度方向分布均匀，保证合金组织性的均匀性，进一步改善合金的高温蠕变性能；此外，渣系较低的熔点使电渣锭易于凝固成型，有效减少或者消除电渣锭的表面缺陷。本发明提供的渣系的熔点、黏度等物性参数均满足电渣重熔冶炼含B型9Cr耐热钢的要求。

The invention relates to a slag system for electroslag remelting of B-type 9Cr heat-resistant steel, which comprises: CaF2: 50 ‑ 60%, Al2O3: 15% ‑ 25%, Cao: 15% ‑ 25%, MgO: 3% ‑ 8%, B2O3: 0.5% ‑ 3%, the balance is impurities, the impurity content is ≤ 1%, and the sum of the above items is 100%; The impurities contain unstable oxide SiO2, which accounts for ≤ 0.8% of the slag system. The slag system can be used for electroslag remelting to produce B-type 9Cr heat-resistant steel, such as cost ‑ FB2 steel or CB2 steel. The use of the slag system can reduce the burning loss of element B, make the B content evenly distributed along the ingot height, ensure the uniformity of alloy microstructure and further improve the high-temperature creep energy of the alloy; In addition, the low melting point of the slag system makes the electroslag ingot easy to solidify and form, which can effectively reduce or eliminate the surface defects of the electroslag ingot. The melting point, viscosity and other physical parameters of the slag system provided by the invention meet the requirements of electroslag remelting smelting B-type 9Cr heat-resistant steel.